Part of the issue is that current disk image dumps are incomplete. The data is there but not the LBA, which you'd need in order to properly access any kind of disk image, be it a floppy or a zip disk like these. A good chunk of it can be 'rebuilt' through careful analysis, but the proper thing to do would be to dump the LBA specific to each disk along with its data to avoid issues. Depending on saved data, etc. they could differ between images.